How do I relate the geometry of a Slitting chisle to the material and size I want to drift?

For example and to clarify the above.

What size slitting chisle If the material is 3/8" (or 3/4" or 1" ) mild steel and I want to pierce it and drift a 1" diameter round hole .

Are there some general rules?

Thanks

There has been extensive coverage on slitters, sizes and geometry if you search for them,

Basic calculations/formula that can be used are:

Round hole, mild steel = dia (finished) + 40%
Square or rectangular hole = perimeter total x .4

John, no offense to you as I'm sure you're correct but when I just did a search for slitters sizes, the results returned only one thread. This one. Perhaps if I'd included geometry the search would have been more successful but I'm not real impressed with this search engine. I did find your reply useful and interesting though which is why I searched in the first place.

Try searching for "slitter geometry" with the " I turned up 10 topics

https://www.google.com/search?q=site%3Aiforgeiron.com+slitter+geometry&rls=com.microsoft:en-us:IE-SearchBox&ie=UTF-8&oe=UTF-8&sourceid=ie7&rlz=1I7ADBF_en#sclient=psy-ab&hl=en&rls=com.microsoft:en-us%3AIE-SearchBox&rlz=1I7ADBF_en&source=hp&q=site:iforgeiron.com+slitter+hole+size&pbx=1&oq=site:iforgeiron.com+slitter+hole+size&aq=f&aqi=&aql=&gs_sm=e&gs_upl=37422l39641l0l39750l17l12l0l0l0l0l375l2484l0.5.5.1l11l0&bav=on.2,or.r_gc.r_pw.,cf.osb&fp=890a274ff6b690bf&biw=1280&bih=796

https://www.google.com/search?q=site%3Aiforgeiron.com+slitter+geometry&rls=com.microsoft:en-us:IE-SearchBox&ie=UTF-8&oe=UTF-8&sourceid=ie7&rlz=1I7ADBF_en#q=site:iforgeiron.com+slitter+geometry&hl=en&rls=com.microsoft:en-us:IE-SearchBox&rlz=1I7ADBF_en&prmd=imvns&ei=vwcGT_TJH8yJsAKbs6mRCg&start=10&sa=N&bav=on.2,or.r_gc.r_pw.,cf.osb&fp=890a274ff6b690bf&biw=1280&bih=796

Uri Hofi did a great BP on the subject